From d3f9cfbdfa0bc8b4354e2a0ae3b927f057642c73 Mon Sep 17 00:00:00 2001
From: Peter Serwylo <peter@serwylo.com>
Date: Mon, 27 Jun 2016 22:41:48 +1000
Subject: [PATCH] Remove need for `temorary b-tree for order by` in most cases
 by introducing two indexes.

The fact that sqlite chose to do a "FULL TABLE SCAN" right off the bat when showing a list
of apps results in it having to do extra work at the end of the query to sort. If the scan
can be utilise an index, then the sorting is already done and a b-tree need not be constructed.
Thus, this introduces indexes for both the `name` column (used to sort most lists of apps)
and the `added` column (used to figure out the `Whats New` apps).
---
 .../java/org/fdroid/fdroid/data/DBHelper.java     | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/app/src/main/java/org/fdroid/fdroid/data/DBHelper.java b/app/src/main/java/org/fdroid/fdroid/data/DBHelper.java
index c688ee01a..677c207e0 100644
--- a/app/src/main/java/org/fdroid/fdroid/data/DBHelper.java
+++ b/app/src/main/java/org/fdroid/fdroid/data/DBHelper.java
@@ -321,18 +321,21 @@ class DBHelper extends SQLiteOpenHelper {
 
     private void migrateAppPrimaryKeyToRowId(SQLiteDatabase db, int oldVersion) {
         if (oldVersion < 58) {
-            final String alter = "ALTER TABLE " + ApkTable.NAME + " ADD COLUMN appId NUMERIC";
-            Log.i(TAG, "Adding appId foreign key to fdroid_apk.");
+            db.execSQL("CREATE INDEX IF NOT EXISTS name ON " + AppTable.NAME + " (" + AppTable.Cols.NAME + ")");
+            db.execSQL("CREATE INDEX IF NOT EXISTS added ON " + AppTable.NAME + " (" + AppTable.Cols.ADDED + ")");
+
+            final String alter = "ALTER TABLE " + ApkTable.NAME + " ADD COLUMN " + ApkTable.Cols.APP_ID + " NUMERIC";
+            Log.i(TAG, "Adding appId foreign key to " + ApkTable.NAME);
             Utils.debugLog(TAG, alter);
             db.execSQL(alter);
 
             final String update =
                 "UPDATE " + ApkTable.NAME + " SET appId = ( " +
-                    "SELECT app.rowid " +
+                    "SELECT app." + AppTable.Cols.ROW_ID + " " +
                     "FROM " + ApkTable.NAME + " AS app " +
-                    "WHERE " + ApkTable.NAME + ".id = app.id " +
+                    "WHERE " + ApkTable.NAME + "." + ApkTable.Cols.PACKAGE_NAME + " = app." + AppTable.Cols.PACKAGE_NAME + " " +
                 ")";
-            Log.i(TAG, "Updating foreign key from fdroid_apk to fdroid_app to use numeric foreign key.");
+            Log.i(TAG, "Updating foreign key from " + ApkTable.NAME + " to " + AppTable.NAME + " to use numeric foreign key.");
             Utils.debugLog(TAG, update);
             db.execSQL(update);
         }
@@ -590,6 +593,8 @@ class DBHelper extends SQLiteOpenHelper {
     private static void createAppApk(SQLiteDatabase db) {
         db.execSQL(CREATE_TABLE_APP);
         db.execSQL("create index app_id on " + AppTable.NAME + " (" + AppTable.Cols.PACKAGE_NAME + ");");
+        db.execSQL("create index name on " + AppTable.NAME + " (" + AppTable.Cols.NAME + ");"); // Used for sorting most lists
+        db.execSQL("create index added on " + AppTable.NAME + " (" + AppTable.Cols.ADDED + ");"); // Used for sorting "newly added"
         db.execSQL(CREATE_TABLE_APK);
         db.execSQL("create index apk_vercode on " + ApkTable.NAME + " (" + ApkTable.Cols.VERSION_CODE + ");");
         db.execSQL("create index apk_appId on " + ApkTable.NAME + " (" + ApkTable.Cols.APP_ID + ");");